High voltage winding



March 19,1940. -.,V E N U 2,194,338

HIGH VOLTAGE WINDING Filed Jan. 18, 1938 Inventor: Jacob d.\/ienneau,

Patented Mar. 19, 1940 PATENT OFFICE HIGH VOLTAGE WINDING Jacob J.Vienneau, Pittsiield, Mass, assignor to General Electric Company, acorporation of New York Application January 18, 1938, Serial No. 185,529

4 Claims.

My invention relates to electrical windings and particularly to themethod of forming the coil structure of a high voltage transformerwinding. The object of my invention is the provision of an improvedmethod of forming such a coil structure employing crepe paper forsupporting and insulating the winding whereby a smaller space factor andgreater insulation at points of greatest voltage stress are possible.

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawing, and its scope will bepointed out in the appended claims.

Referring to the drawing, Fig. 1 represents a press by which sheets ofcrepe paper may be precompressed; Fig. 2 shows a sheet comprising anumber of superposed layers of crepe paper after they have beenpro-compressed; Fig. 3 represents that step in the method whichcomprises the moistening of portions of the crepe paper cylinder; Fig. 4is an enlarged portion of Fig. 3

showing the crepe paper after it has been moistened and turned outwardlyto form a flange, and Fig. 5 shows a modification.

In order to reduce the thickness of the crepe paper which is employed tosupport and insulate the high voltage winding and upon which the windingis wound I first compress it, the amount of such compression beingdependent upon various factors which amount may, for example, besuflicient to reduce the thickness of the paper to approximately 50 percent or less of its original thickness. This has the important advantagethat it provides a better space factor for the winding. Various meansmay be employed for giving the crepe paper the desired amount ofcompression and preferably a. number of superposed sheets are compressedin one operation. For the purpose of illustrating this step I have shownin Fig. 1 the hand press 1 the pressure plates of which preferably areheated for effecting this compression of the sheets of crepe paperrepresented at 2; however, it will be understood that in actual practiceI prefer to employ a power press for obvious reasons. In assembling theseveral sheets of crepe paper in the press prior to compressing themcare is to be taken to arrange the sheets with the corrugations thereofall extending in the same direction. As a result of the compression theseveral sheets of crepe paper become united with each other to form afirm laminated sheet whose thickness is only a fractional part of thesum total thickness of the sheets of crepe paper before compression.

The sheet of compressed crepe paper illustrated at 3 in Fig. 2 is thenbent or rolled up in the form of a cylinder 4 preferably by rolling iton a cylinder of insulation, as shown at 5, the outer end being suitablysecured to prevent unrolling. In so bending or rolling the sheet of com-5 pressed paper the paper is arranged so that the corrugations extendaxially of the cylinder.

'The winding represented at B is then wound on the paper cylinder in theusual manner, the ends of the cylinder being left projecting beyond theill winding. For convenience in applying the winding and for a furtherreason to be explained'later,

I have shown the insulation cylinder 5 supported on centers whereby itmay be rotated as desired. The winding having been completed, thefoldededge paper 7, the spacers 8, and the insulating rings 9 areapplied in accordance with the well known construction of windings ofthis type.

The next step of the process is to moisten the end portions of the crepepaper cylinder, i. e. 49 those portions which extend beyond the limitsof the winding. A convenient way of moistening these end portions is toapply a spray or jet it of water thereto while the complete winding assembly is rotated. The compressed crepe paper quickly soaks up the waterwhich causes it to swell to approximately its original thickness andmake it sufiiciently flexible that it can be readily deformed withoutbreaking the paper.

While the end portion of the paper cylinder is in a moistenedcondition,it is flared outwardly to form an end flange. ihis step may be performedby the use of a suitable tool applied to the end of the cylinder whichwill cause it to flare or what is preferable may be produced bycentrifugal force as the result of rotating the entire assembly withsufficient speed. The flared end portion of .the paper cylinder willthus he along the side of the outerring 9 as shown for example at Fig.4. The moistened portion of the paper may be allowed to dry by theevaporation of the moisture without movement of the assembly but Iprefer to hasten it by continuing the rapid rotation of the assembly bywhich the surplus moisture is thrown on and drying takes place quiterapidly. For holding the flared portion in proper position after itbecomes dry, I have shown an additional end ring II which may be pushedover the inner insulation ring 5.

By reference to Fig. 4 it will be seen that the crepe paper insulationis continuous from that portion beneath the winding to that portionforming the flange #2, Also, that part of the insultion namely at thejuncture of the cylinrical part and the flanged part is approximatelyiiii portion I3.

twice the thickness of the cylindrical part. This is an importantadvantage inasmuch as it is well known to those skilled in the art thatthe most difilcult part of a structure of this kind to insulate is thatpart comprising the juncture between the flange and the cylinder. As aresult of this construction the dielectric strength at the point whereinsulation is the most necessary is substantially increased over thedielectric strength of the solid insulation directly below the winding,inv other words, between the winding and the yoke, inasmuch as thedielectric strength in a given space is higher, when occupied by oil andlaminated paper, than when there is only a single dense barrier incombination with an oil duct in the remaining space.

The above described process for expanding and forming an integral flangeat one end of the paper cylinder obviously is employed for producing asimilar flange atthe other end of the cylinder.

In certain cases and in certain forms of winding it is not necessary tohave the cylinder of compressed paper extend the-entire length 01. thewinding but need extend only for a few turns at the ends of the winding.In certain cases also it is desirable that the expanded part of thecompressed paper should not only form a flange .at the end of thewinding but also overlie some of the outer turns at the end of thewinding.

This has been illustrated by Fig. 5 where the paper in its compressedform supports the end turns of the winding, and the expanded portion ofthe paper forms the end .flange and overlying What I claim as new anddesire to secure by Letters Patent of the United States is:

1. The method of forming a flanged member of crepe paper for supportingand insulating a high voltage winding which comprises initiallycompressing a sheet of said paper to reduce its thickness, bending thecompressed sheet into cylindrical form with the line of the corrugationsof the paper extending axially, moistening an end portion of thecylinder thereby restoring the paper substantially to its originalthickness and turning the moistened portion outwardly to form a flange.

2. The method of forming a high voltage coil structure employing cr pepaper as a supporting and insulating medium which comprises initiallycompressing a sheet of the paper uniformly to increase the densitythereof, bending the compressed paper into cylindrical form with thecorrugations extending axially, applying a winding to cover a part onlyof said cylinder, moistening another part thereof substantially torestore its original density and turning said other part outwardly toform a flange. I

3. The method of forming a high voltage coil structure employing crepepaper as a supporting and insulating medium which comprises initiallycompressing a sheet of said crepe paper uniformly to materially reduceits thickness, wrapping the compressed sheet of paper about acylindrical support with the corrugations extending axially, winding aconductor on a part only thereof, moistening a part of the papercylinder projecting beyond the winding whereby its thickness increasesand bending said thickened part outwardly to form a flange.

4. The method of forming an insulating cylinder having a thick flangeemploying crepe paper extending in continuous layers throughout thecylindrical and flange portions which comprises initially and uniformlycompressing a sheet of said paper, forming the compressed sheet into acylinder with the corrugations extending axially, wetting an end portionof the cylinder thereby to cause said portion to soften and swell andturning outwardly said end portion to form the thick flange.

. JACOB J. VIENNEAU.

